Cases of word usage

1) a bar going across, e.g. joining the two posts of a goal in football etc or the front and back parts of a bicycle (crossbar)

2) a bicycle fitted with a small petrol engine (moped)

3) relating to a ray, rays or a radius; (of spokes in a bicycle wheel etc) arranged like rays or radii (radial)

4) something that reflects heat, light or sound, e.g. a piece of glass for reflecting light on the back of a bicycle (reflector)

5) a seat for a rider on a horse, donkey or bicycle (saddle)

6) a bicycle made for two people to ride on with pedals for both (tandem)